Flue gas purification system

Abstract

The invention discloses a flue gas purification system, and aims to solve the technical problem of gas backflow caused by untight sealing of front and rear valves of induced draft fans when different induced draft fans of a flue gas driving device of the flue gas purification system are switched. Comprising a flue gas purification device and a flue gas driving device used for driving flue gas to be treated to pass through the flue gas purification device, and the flue gas driving device comprises at least two induced draft fans which are arranged between a flue gas main input pipeline and a flue gas main output pipeline in parallel; an inlet of each of the at least two induced draft fans is connected with the flue gas main input pipeline through a first non-return liquid seal device which is independently arranged, and an outlet of each of the at least two induced draft fans is connected with the flue gas main output pipeline through a second non-return liquid seal device which is uniformly arranged. The problem of gas backflow possibly caused by untight sealing of a conventional valve during switching of the induced draft fan is solved.

Description

Technical Field

[0001] The invention relates to the technical field of flue gas treatment, and in particular to a catalytic flue gas treatment device, a yellow phosphorus tail gas purification system and a flue gas purification system. Background Art

[0002] In order to remove sulfur dioxide from the flue gas to be treated, the applicant has developed a catalytic flue gas treatment technology. For example, the applicant has disclosed catalytic flue gas desulfurization equipment in patent documents with publication numbers CN214764545U, CN114653202A, and CN114797450A. However, their use is limited to the removal of sulfur dioxide.

[0003] On the other hand, yellow phosphorus tail gas is a process gas mainly containing carbon monoxide, which is discharged after the phosphorus collection process in the electric furnace yellow phosphorus production process. In addition to CO, the gas usually also contains impurities such as P4, CO2, PH3, O2, COS, CS2, H2S, water vapor, HF, etc. At present, the main methods for purifying yellow phosphorus tail gas are:

[0004] 1) Water washing method: Introduce yellow phosphorus tail gas into a water washing tower to remove most of the dust and fluoride, phosphide and sulfide;

[0005] 2) Alkali washing method: Introduce the yellow phosphorus tail gas into the alkaline washing tower and wash it with NaOH solution to remove a large amount of acidic gases such as H2S and CO2 in the tail gas;

[0006] 3) Temperature swing adsorption (TSA): Use temperature changes to control the adsorption and desorption process, adsorption at low temperature, desorption and regeneration at high temperature, mainly used for dephosphorization;

[0007] 4) Pressure swing adsorption (PSA): using pressure changes to control the adsorption and desorption process, high pressure adsorption, low pressure desorption regeneration, mainly used to remove H2S and CO2 in yellow phosphorus tail gas;

[0008] 5) DePOx continuous catalytic oxidation dephosphorization process: a continuous treatment process that uses a selective catalyst to oxidize PH3 in yellow phosphorus tail gas into elemental phosphorus and water at 200-300°C and near normal pressure by precisely controlling the amount of oxygen;

[0009] 6) For phosphine and hydrogen sulfide in yellow phosphorus tail gas, there are also ferric chloride method, sodium hypochlorite oxidation method, concentrated sulfuric acid absorption method, and hydrogen peroxide oxidation method. They all use chemical oxidants (FeCl3, NaClO, H2SO4, H2O2) to oxidize PH3 and H2S into harmless or easy-to-handle products, so they can be collectively referred to as chemical oxidant oxidation methods.

[0010] At present, most manufacturers adopt a combination of water washing and alkaline washing processes. A small number of manufacturers, based on the water washing and alkaline washing processes, also add temperature swing adsorption (TSA), pressure swing adsorption (PSA), DePOx continuous catalytic oxidation dephosphorization process, and chemical oxidant oxidation process.

[0011] In the prior patent application document with application number 202411874384X and titled "Method and Equipment for Dephosphorization and Desulfurization of Yellow Phosphorus Tail Gas", the applicant provides a new method and equipment for dephosphorization and desulfurization of yellow phosphorus tail gas (see the specific introduction in the specific implementation method section of this specification), which adopts a three-stage catalytic flue gas treatment: the first stage converts PH3 and P4 into controllable phosphorus oxides and phosphoric acid through catalytic oxidation; the second stage converts organic sulfur (such as COS, CS2) into H2S through catalytic hydrolysis; the third stage catalytically oxidizes H2S to elemental S. The entire treatment process can achieve efficient and continuous treatment of phosphorus-containing pollutants and sulfur-containing pollutants in yellow phosphorus tail gas through the selective reaction of the catalyst. In addition, in view of the problem that elemental S is easily oxidized to form sulfur dioxide, thereby causing secondary pollution, the third catalyst can further catalytically oxidize sulfur dioxide and react with water to form sulfuric acid, thereby avoiding the problem of sulfur dioxide emissions.

[0012] The yellow phosphorus tail gas dephosphorization and desulfurization method and equipment still have the following problems: in order to drive the yellow phosphorus tail gas when the system is running, a flue gas driving device is also provided in the system, and the flue gas driving device usually includes two induced draft fans (one for backup and one for use) arranged in parallel between the total flue gas input pipeline and the total flue gas output pipeline, and valves are provided at the inlet and outlet of each induced draft fan. At present, the switching between induced draft fans is achieved by the opening and closing control of these valves. However, it is difficult for these valves to be completely sealed, and the yellow phosphorus tail gas is a flammable, explosive and highly toxic gas. When the switching between induced draft fans is achieved by the opening and closing control of these valves, backflow is prone to occur, which poses certain safety hazards. Summary of the invention

[0013] The object of the present invention is to provide a flue gas purification system to solve the technical problem of gas backflow caused by poor sealing of valves before and after the induced draft fans when switching between different induced draft fans of the flue gas driving device of the flue gas purification system (such as the yellow phosphorus tail gas purification system).

[0014] A flue gas purification system is provided, comprising a flue gas purification device and a flue gas driving device for driving the flue gas to be treated to pass through the flue gas purification device, the flue gas driving device comprising at least two induced draft fans arranged in parallel between a total flue gas input pipe and a total flue gas output pipe, the inlet of each of the at least two induced draft fans being connected to the total flue gas input pipe via an independently arranged first non-return liquid sealing device, and the outlet of each of the at least two induced draft fans being connected to the total flue gas output pipe via a uniformly arranged second non-return liquid sealing device.

[0015] By arranging an independent first anti-return liquid sealing device at the inlet of the induced draft fan and a unified second anti-return liquid sealing device at the outlet, the problem of gas backflow caused by poor sealing of conventional valves when the induced draft fan is switched is cleverly solved.

[0016] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments. Additional aspects and advantages provided by the present invention will be partially given in the following description, partially become apparent from the following description, or be learned through practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings constituting a part of this specification are used to assist the understanding of the present invention. The contents provided in the drawings and the related descriptions in this specification can be used to explain the present invention, but do not constitute improper limitations on the present invention.

[0018] Figure 1 This is a schematic diagram of a yellow phosphorus tail gas purification system according to an embodiment of the present invention.

[0019] Figure 2 for Figure 1 A partial enlarged view of the flue gas drive device.

[0020] Figure 3 for Figure 1 A partial enlarged view of the dephosphorization device. DETAILED DESCRIPTION

[0021] The present invention is described clearly and completely below in conjunction with the accompanying drawings. A person skilled in the art will be able to implement the present invention based on these descriptions. Before describing the present invention in conjunction with the accompanying drawings, it should be particularly noted that:

[0022] The technical solutions and technical features provided in each section, including the following description, can be combined with each other without conflict. In addition, where possible, these technical solutions, technical features and related combinations can be assigned specific technical themes and protected by relevant patents.

[0023] The embodiments of the present invention involved in the following description are generally only a part of the embodiments rather than all the embodiments. Based on these embodiments, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of patent protection.

[0024] The terms "include", "comprises", "have" and any variations thereof in this specification and the corresponding claims and related parts are intended to cover non-exclusive inclusions. Other related terms and units can be reasonably interpreted based on the relevant content provided in this specification.

[0025] Figure 1 Schematic diagram of a yellow phosphorus tail gas purification system according to an embodiment of the present invention. Figure 1 As shown, the yellow phosphorus tail gas purification system mainly includes: a dephosphorization device 7, an organic sulfur hydrolysis conversion device 8 and a desulfurization device 9.

[0026] The dephosphorization device 7 is used to receive yellow phosphorus tail gas and remove phosphorus-containing substances in the yellow phosphorus tail gas. The dephosphorization device 7 adopts a first catalytic flue gas treatment device, which includes a first reactor 71. During operation, the yellow phosphorus tail gas enters the first reactor 71 from the air inlet of the first reactor 71, passes through the first catalyst, and is then discharged from the exhaust port of the first reactor 71 to become dephosphorized flue gas. PH3 and P4 in the yellow phosphorus tail gas react on the first catalyst to form phosphorus oxides and phosphoric acid when passing through the first catalyst. When the first catalyst is washed and regenerated, the phosphorus oxides and the phosphoric acid enter the regeneration liquid sprayed on the first catalyst and are discharged from the discharge port of the first reactor 71.

[0027] The organic sulfur hydrolysis conversion device 8 is used to receive the dephosphorized flue gas and convert the organic sulfur in the dephosphorized flue gas into H2S. The organic sulfur hydrolysis conversion device 8 adopts a second catalytic flue gas treatment device, and the second catalytic flue gas treatment device includes a second reactor 81. During operation, the dephosphorized flue gas enters the second reactor 81 from the air inlet of the second reactor 81, passes through the second catalyst, and is discharged from the exhaust port of the second reactor 81 to become organic sulfur hydrolysis conversion flue gas. The organic sulfur in the dephosphorized flue gas is hydrolyzed and converted into H2S when passing through the second catalyst.

[0028] The desulfurization device 9 is used to receive the organic sulfur hydrolysis conversion flue gas and remove H2S in the organic sulfur hydrolysis conversion flue gas. The desulfurization device 9 adopts a third catalytic flue gas treatment device, and the third catalytic flue gas treatment device includes a third reactor 91. During operation, the organic sulfur hydrolysis conversion flue gas enters the third reactor 91 from the air inlet of the third reactor 91, passes through the third catalyst, and is then discharged from the exhaust port of the third reactor 91 to become desulfurized flue gas. The H2S in the organic sulfur hydrolysis conversion flue gas reacts on the third catalyst to form elemental S and sulfuric acid when passing through the third catalyst. The sulfuric acid is generated by further catalytic oxidation of sulfur dioxide generated by the reaction of the elemental S with oxygen and reacting with water. When the third catalyst is washed and regenerated, the elemental S and the sulfuric acid enter the regeneration liquid sprayed on the third catalyst and are discharged from the discharge port of the third reactor 91.

[0029] The above-mentioned yellow phosphorus tail gas dephosphorization and desulfurization equipment adopts a three-stage catalytic flue gas treatment method: the first stage converts PH3 and P4 into controllable phosphorus oxides and phosphoric acid through catalytic oxidation; the second stage converts organic sulfur (such as COS, CS2) into H2S through catalytic hydrolysis; the third stage catalytically oxidizes H2S to elemental S. The entire treatment process can achieve efficient and continuous treatment of phosphorus-containing pollutants and sulfur-containing pollutants in yellow phosphorus tail gas through the selective reaction of the catalyst. In addition, in order to solve the problem that elemental S is easily oxidized to form sulfur dioxide and cause secondary pollution, the third catalyst can further catalytically oxidize sulfur dioxide and react with water to form sulfuric acid, thereby avoiding the emission of sulfur dioxide.

[0030] More specifically, the above three-stage catalytic flue gas treatment has the following coupling effects: First, phosphides (especially PH3 and P4) are toxic in themselves and will poison the subsequent catalysts (phosphides such as PH3 and P4 have strong reducing and coordination properties. When they come into contact with the catalyst surface, they are prone to certain chemical adsorption and chemical reactions with the catalyst active sites, thereby occupying or covering the catalyst active sites). Therefore, by preferentially removing phosphides, the activity and service life of the subsequent second and third catalysts can be effectively protected. Secondly, organic sulfur is uniformly converted into H2S through the second-stage catalytic hydrolysis. Compared with organic sulfides such as COS and CS2, H2S is more easily catalytically oxidized, which can significantly improve the desulfurization efficiency of the third stage. Finally, the temperature gradient and chemical reaction characteristics of the entire treatment chain form a good synergistic effect.

[0031] like Figure 1 As shown, the above-mentioned yellow phosphorus tail gas dephosphorization and desulfurization equipment can also include a leaching pretreatment device, which is arranged before the dephosphorization device 7, and the leaching pretreatment device is used to perform leaching pretreatment on the yellow phosphorus tail gas before sending it into the dephosphorization device 7; the leaching pretreatment includes a first leaching system 1 and / or a second leaching system 2, the first leaching system 1 is used to perform water leaching treatment on the yellow phosphorus tail gas, and the second leaching system 2 is used to perform alkaline solution leaching treatment on the yellow phosphorus tail gas.

[0032] Specifically, in this embodiment, the elution pretreatment includes a first elution system 1 and a second elution system 2, wherein the first elution system 1 includes two-stage first elution towers, and the second elution system 2 includes one-stage second elution tower, and the second elution tower is arranged in series after the two-stage first elution towers.

[0033] The elution pretreatment device is mainly used to remove large particulate matter and some water-soluble gaseous pollutants in yellow phosphorus tail gas. Water elution treatment can preliminarily remove some phosphorus- and sulfur-containing compounds, and alkaline solution elution treatment can further remove acidic gases, thereby reducing the load of subsequent treatment.

[0034] In addition, a gas-liquid separation device 3 and a gas heating device are sequentially arranged between the leaching pretreatment device and the dephosphorization device 7. The function of the gas-liquid separation device 3 is to achieve gas-liquid separation, and the separated yellow phosphorus tail gas can first enter the gas separation cylinder 4, and the gas separation cylinder 4 can shunt the yellow phosphorus tail gas as needed. For example, the gas separation cylinder 4 can shunt a part of the yellow phosphorus tail gas to a gas tank for storage (the yellow phosphorus tail gas in the gas tank can be used for combustion) and shunt a part of the yellow phosphorus tail gas to the gas heating device.

[0035] The gas separation cylinder 4 is arranged after the gas-liquid separation device 3 and before the gas heating device, and can divert the yellow phosphorus tail gas according to actual needs, which not only realizes the rational use of resources, but also avoids overloading of subsequent catalytic treatment devices.

[0036] In this embodiment, the gas heating device specifically includes a heat exchanger 5 and a heater 6. The function of the heat exchanger 5 is to use the yellow phosphorus tail gas output by the desulfurization device 9 to preheat the yellow phosphorus tail gas output by the gas cylinder 4, and the function of the heater 6 is to use external water vapor to further heat the yellow phosphorus tail gas preheated by the heat exchanger 5.

[0037] The gas heating device adopts a two-stage heating method of a heat exchanger 5 and a heater 6. This design not only saves energy but also ensures that the yellow phosphorus gas entering the dephosphorization device 7 reaches a suitable reaction temperature.

[0038] In summary, the working process of the above-mentioned yellow phosphorus tail gas dephosphorization and desulfurization equipment is as follows: the yellow phosphorus tail gas first passes through the first elution system (including two-stage first elution towers) for water elution treatment and the second elution system (including one-stage second elution tower) for alkaline solution elution treatment, and then enters the gas separation cylinder 4 after separation by the gas-liquid separation device 3. The gas separation cylinder 4 diverts part of the yellow phosphorus tail gas to the gas tank for storage for combustion, and the other part is heated by the heat exchanger 5 (preheating the yellow phosphorus tail gas output by the desulfurization device 9) and the heater 6, and then enters the dephosphorization device 7 (PH3 and P4 react on the first catalyst to form phosphorus oxides and phosphoric acid), the organic sulfur hydrolysis conversion device 8 (organic sulfur is hydrolyzed on the second catalyst to form H2S) and the desulfurization device 9 (H2S reacts on the third catalyst to form elemental S and sulfuric acid), and is finally discharged as desulfurized flue gas.

[0039] It should be pointed out that the above-mentioned first catalytic flue gas treatment device, the second catalytic flue gas treatment device and the third catalytic flue gas treatment device all use catalytic method to treat flue gas. From the process principle point of view, each of them is not a brand new technology (for example, there is a technology for catalytic hydrolysis of organic sulfur into hydrogen sulfide in the field of natural gas purification), but the key lies in the combination method and the selection of suitable catalysts and operating process parameters according to the combined process.

[0040] In this embodiment, the operating conditions of the first reactor are:

[0041] 1) First catalyst formula:

[0042] The first catalyst is mainly composed of the following components in parts by weight uniformly mixed:

[0043] Nano PdO particles: 0.8-1.2 parts;

[0044] Nano PtO2 particles: 0.4-0.6 parts;

[0045] CeO2: 3.5-4.5 parts;

[0046] V2O5: 2.5-3.5 parts;

[0047] Activated carbon carrier: 90-93 parts;

[0048] Wherein, the weight ratio of nano-PdO particles to nano-PtO2 particles is (1.8-2):1, and the weight ratio of CeO2 to V2O5 is (1.2-1.5):1;

[0049] 2) Operation parameters of the first reactor: operate at 100-120℃, control the air velocity to 1000-2000h -1 , O2 concentration in the gas phase is 5-8% (v / v%), and the moisture content is less than 2% (v / v%).

[0050] It can be seen that the first catalyst is mainly composed of nano-PdO particles, nano-PtO2 particles, CeO2, V2O5 and activated carbon carrier, wherein the weight ratio of nano-PdO to nano-PtO2 is controlled at (1.8-2):1, and the weight ratio of CeO2 to V2O5 is controlled at (1.2-1.5):1. Under the conditions of 100-120℃ and the space velocity of 1000-2000h -1 , it operates under the conditions of O2 concentration of 5-8% (v / v%) in the gas phase and moisture content less than 2% (v / v%).

[0051] Nano-scale PdO and PtO2 are the main active components in the first catalyst, which have excellent oxidation catalytic performance and can efficiently catalyze the oxidation conversion of PH3 and P4; CeO2 has good oxygen storage and release performance and redox performance, and can provide active oxygen for the reaction; V2O5 can improve the sulfur resistance of the catalyst; and the activated carbon carrier provides a large specific surface area, which is conducive to the dispersion of active components and the adsorption of reactants. The overall formula design achieves efficient catalytic oxidation of phosphorus-containing pollutants.

[0052] Specifically, CeO2 has a unique fluorite crystal structure, Ce ions can reversibly switch between +3 and +4 valence states, and lattice oxygen can freely enter and exit the lattice to form oxygen vacancies. Under oxygen-rich conditions, CeO2 can absorb and store oxygen.3+ Oxidized to Ce 4+ ; Under hypoxic conditions, Ce 4+ It will release oxygen and reduce to Ce 3+ This oxygen storage and release process can be expressed as: This property enables CeO2 to regulate the local oxygen concentration and continuously provide active oxygen for the catalytic oxidation reaction, thereby maintaining stable catalytic activity. The oxygen vacancies on the CeO2 surface can serve as active sites, promoting the activation of oxygen molecules and improving the catalytic oxidation efficiency.

[0053] V2O5 forms a VOV structure in the catalyst, which has a strong resistance to sulfur poisoning. When sulfur-containing compounds come into contact with the catalyst, the sulfate formed on the surface of V2O5 is easier to decompose and will not accumulate on the catalyst surface to form stable sulfides, thus avoiding permanent deactivation of active sites. In addition, there is a strong interaction between V2O5 and CeO2, forming a Ce-OV bridge bond structure, which further enhances the redox performance and sulfur resistance of the catalyst. During the catalyst regeneration process, V2O5 also helps to oxidize and remove sulfides, allowing the catalyst to continue to maintain high activity.

[0054] The reaction formulas involved in the first reactor are: 4PH3+8O2→2P2O5+6H2O; P4+5O2→P2O5;

[0055] P2O5+3H2O→2H3PO4.

[0056] In this embodiment, the operating conditions of the second reactor are:

[0057] 1) Second catalyst formula:

[0058] The second catalyst is mainly composed of the following components in parts by weight uniformly mixed:

[0059] CeO2: 5-7 parts;

[0060] V2O5: 3-4 parts;

[0061] MoO3: 2-3 parts;

[0062] γ-Al2O3 carrier: 86-90 parts;

[0063] Among them, the weight ratio of CeO2 to V2O5 is (1.6-1.8):1, and the weight ratio of V2O5 to MoO3 is (1.4-1.6):1;

[0064] 2) Operation parameters of the second reactor: operate at 70-90°C and control the air velocity to 1000-2000h -1 , the moisture content is 15-20% (v / v%).

[0065] It can be seen that the second catalyst is mainly composed of CeO2, V2O5, MoO3 and γ-Al2O3 carrier, wherein the weight ratio of CeO2 to V2O5 is (1.6-1.8):1, and the weight ratio of V2O5 to MoO3 is (1.4-1.6):1. Under the condition of 70-90℃ and the space velocity of 1000-2000h -1 , and operate under the condition of moisture content 15-20% (v / v%).

[0066] CeO2 through Ce 4+ / Ce 3+ The valence state conversion provides sufficient redox active sites and forms a stable Ce-OV structure with V2O5 to enhance the anti-poisoning ability; V2O5 provides an appropriate amount of acidic sites to promote the hydrolysis reaction, and its V-OH group can activate water molecules to accelerate the hydrolysis process; MoO3 not only 6+ It provides additional Lewis acid sites to enhance hydrolysis activity, effectively inhibits sulfur poisoning and forms a Mo-O-Ce structure with other components; the γ-Al2O3 carrier has a large specific surface area (>200m 2 / g) and suitable pore structure ensure that the active components are highly dispersed while providing excellent mechanical strength and thermal stability. The precise ratio of the three active components (CeO2:V2O5=(1.6-1.8):1, V2O5:MoO3=(1.4-1.6):1) ensures the optimal balance between acidic sites and redox sites, achieving efficient and stable hydrolysis conversion of organic sulfur under low temperature conditions.

[0067] The hydrolysis conversion process includes the following reaction formulas: COS+H2O=H2S+CO2 and CS2+2H2O=2H2S+CO2.

[0068] In this embodiment, the operating conditions of the third reactor are:

[0069] 1) The third catalyst formula:

[0070] The third catalyst is mainly composed of the following components in parts by weight uniformly mixed:

[0071] Fe2O3: 3-5 parts;

[0072] CuO: 2-3 parts;

[0073] MnO2: 1-2 parts;

[0074] Activated carbon carrier: 90-94 parts;

[0075] Wherein, the weight ratio of Fe2O3 to CuO is (1.5-1.8):1, and the weight ratio of CuO to MnO2 is (1.8-2.0):1;

[0076] 2) Operation parameters of the third reactor:

[0077] Run at 65-85℃, control airspeed at 800-1500h -1 , the O2 concentration in the gas phase is 3-5% (v / v%), and the moisture content is 2-8% (v / v%).

[0078] The third catalyst is mainly composed of Fe2O3, CuO, MnO2 and activated carbon carrier, wherein the weight ratio of Fe2O3 to CuO is (1.5-1.8):1, and the weight ratio of CuO to MnO2 is (1.8-2.0):1. Under the condition of 65-85℃, the space velocity is 800-1500h -1 , it operates under the conditions of 3-5% (v / v%) O2 concentration in the gas phase and 2-8% (v / v%) moisture content.

[0079] The third catalyst is actually divided into a first component and a second component. The first component includes Fe2O3, CuO, and MnO2, and is used to catalyze the reaction of H2S and oxygen in the flue gas to be treated to generate elemental S. The second component includes an activated carbon carrier, and is used to further catalytically oxidize the sulfur dioxide generated by the reaction of the elemental S and oxygen and react with water to generate sulfuric acid.

[0080] Fe2O3 is the main active component. 3+ / Fe 2+ Valence state cycle catalyzes H2S oxidation; CuO via Cu 2+ / Cu + The conversion enhances the efficiency of electron transfer; MnO2 provides additional redox sites. The precise ratio of the three oxides (Fe2O3:CuO=(1.5-1.8):1, CuO:MnO2=(1.8-2.0):1) forms an efficient multi-metal oxide composite system, which realizes the selective oxidation of H2S to elemental sulfur at low temperature (65-85℃). The appropriate oxygen concentration and water content during the reaction are conducive to maintaining the catalytic cycle and inhibiting over-oxidation.

[0081] Activated carbon not only provides a large specific surface area to disperse active components as a carrier, but more importantly, its surface oxygen-containing functional groups play a key role in the second-stage reaction. When a small amount of elemental sulfur is over-oxidized to generate SO2, the oxygen-containing functional groups on the surface of activated carbon can catalyze the further oxidation of SO2 and convert it into sulfuric acid in the presence of water, thereby achieving deep desulfurization. This dual-functional catalytic system not only ensures the efficient removal of H2S under low temperature conditions, but also can process the SO2 generated during the process, reflecting the integrity and advancement of the catalyst design.

[0082] It can be seen that the three-stage catalytic flue gas treatment implemented by the above-mentioned yellow phosphorus tail gas dephosphorization and desulfurization equipment belongs to low-temperature catalytic technology (the first reactor is operated at 100-120°C, the second reactor is operated at 70-90°C, and the third reactor is operated at 65-85°C), and the temperature of the three-stage catalytic flue gas treatment is reduced step by step. This temperature gradient design reduces energy consumption (heater 6 can use a steam heater, and the steam source required by the steam heater is already available in the yellow phosphorus manufacturer and can be used directly; and the yellow phosphorus tail gas does not need to be heated except for heater 6), while avoiding the catalyst sintering deactivation caused by excessive temperature.

[0083] The above desulfurization device specifically includes: reaction system, regeneration liquid circulation system and flue gas transportation system. Figure 1 It can be seen that the above-mentioned dephosphorization device also includes a reaction system, a regeneration liquid circulation system and a flue gas conveying system. The following will focus on the reaction system, the regeneration liquid circulation system and the flue gas conveying system of the desulfurization device.

[0084] The reaction system of the desulfurization device is used for reacting and removing H2S in the flue gas to be treated, and comprises at least one reactor (i.e., the third reactor 91). The reactor has an air inlet, an exhaust port, a liquid discharge port and a catalyst (i.e., the third catalyst) located in the reactor. The reactor is provided with a regeneration liquid spraying device for washing and regenerating the catalyst. During operation, the flue gas to be treated enters the reactor from the air inlet of the reactor, passes through the catalyst, and is then discharged from the exhaust port of the reactor to become treated flue gas. When passing through the catalyst, the H2S in the flue gas to be treated reacts on the catalyst to form elemental S and sulfuric acid. The sulfuric acid is generated by further catalytic oxidation of sulfur dioxide generated by the reaction of the elemental S with oxygen and reacting with water. When the catalyst is washed and regenerated, the elemental S and the sulfuric acid enter the regeneration liquid sprayed on the catalyst and are then discharged from the liquid discharge port of the reactor.

[0085] The regeneration liquid circulation system comprises at least one regeneration liquid tank and a regeneration liquid circulation control pipeline network connected between the at least one regeneration liquid tank and each reactor, wherein the regeneration liquid circulation control pipeline network comprises an output side control pipeline network, an input side control pipeline network and a regeneration liquid driving device, wherein the output side control pipeline network can introduce the regeneration liquid in the selected regeneration liquid tank into the regeneration liquid spraying device of the selected reactor, and the input side control pipeline network can introduce the regeneration liquid output from the discharge port of the selected reactor into the selected regeneration liquid tank, and the regeneration liquid driving device can provide the required power to the regeneration liquid.

[0086] The flue gas delivery system comprises an air intake network and an exhaust network, wherein the air intake network comprises an air intake main pipe and air intake branches respectively connecting the air intake main pipe with the air intake ports of the reactors, and each air intake branch pipe is provided with an on-off control mechanism, and the exhaust network comprises an exhaust main pipe and exhaust branches respectively connecting the exhaust main pipe with the exhaust ports of the reactors.

[0087] Among them, each air intake branch pipe has a bending portion that extends downward, then turns back and extends upward. When it is necessary to cut off the air intake of the smoke in the selected air intake branch pipe, a liquid sealing liquid is injected into the corresponding bending portion through a liquid inlet structure arranged on the corresponding bending portion to form a liquid seal for the bending portion. When it is necessary to conduct the air intake of the smoke in the selected air intake branch pipe, the liquid sealing liquid in the corresponding bending portion is discharged through a liquid discharge structure arranged on the corresponding bending portion.

[0088] The above structure of the desulfurization device can refer to the relevant structures of the catalytic flue gas desulfurization equipment involved in the patent documents with publication numbers CN214764545U, CN114653202A, CN114797450A, etc. The working process of the desulfurization device in the present invention and the catalytic flue gas desulfurization equipment in these patent documents is similar.

[0089] As mentioned above, the working process of the yellow phosphorus tail gas dephosphorization and desulfurization equipment of the above embodiment is as follows: the yellow phosphorus tail gas is firstly subjected to water elution treatment by the first elution system and alkaline solution elution treatment by the second elution system, and then enters the gas cylinder 4 after separation by the gas-liquid separation device 3. The gas cylinder 4 diverts part of the yellow phosphorus tail gas to the gas cabinet for storage for combustion, and the other part is heated by the heat exchanger 5 and the heater 6, and then enters the dephosphorization device 7, the organic sulfur hydrolysis conversion device 8 and the desulfurization device 9 in sequence, and finally discharged as desulfurized flue gas. The experiment found that after the yellow phosphorus tail gas is washed with water and alkali, it still contains more inorganic sulfur (H2S) and organic sulfur (COS, CS2, etc.). The composition and content of these sulfides depend on the nature and quality of the raw materials, and H2S will react with oxygen to generate sulfur element, which is a yellow solid and will be deposited on the surface of the first catalyst, increasing the resistance of the first catalyst layer.

[0090] Therefore, the yellow phosphorus tail gas dephosphorization and desulfurization equipment according to another embodiment of the present invention improves the above yellow phosphorus tail gas dephosphorization and desulfurization equipment by adding a pre-desulfurization device before the dephosphorization device 7.

[0091] The pre-desulfurization device can adopt a liquid phase absorption process, the core principle of which is to use a proprietary liquid phase desulfurizer to absorb H2S into a rich liquid in the desulfurization tower; the rich liquid (stored in a rich liquid tank) is regenerated by contact with air in the ejector, and is restored to a lean liquid before returning to the desulfurization tower through the lean liquid tank for use.

[0092] This liquid phase desulfurizer can use a mixed solution of sodium carbonate and sodium arsenite, which reacts with HS to generate NaHS and NaHCO during the absorption process, and then undergoes an oxidation regeneration reaction when in contact with air in the ejector, while precipitating elemental sulfur; the NaOH generated during the regeneration process reacts with CO in the air to regenerate NaCO, thereby realizing the recycling of the liquid phase desulfurizer. The pre-desulfurization device can be operated at room temperature and pressure, and has the characteristics of simple operation and high efficiency. Sodium arsenite (NaAsO) is an active component (the dosage is generally a few grams / liter) and plays a catalytic role to improve the regeneration efficiency and reaction rate: it is reduced to arsenic when absorbing HS, and is oxidized back to sodium arsenite when in contact with air, and this cycle is repeated.

[0093] Of course, the pre-desulfurization device can also be the same as the desulfurization device. In an optional embodiment, the desulfurization device is a desulfurization tower, and a plurality of reactors are distributed in the desulfurization tower, some of which are used as reactors of the pre-desulfurization device, and the other part are used as reactors of the desulfurization device.

[0094] like Figure 1 As shown, in the yellow phosphorus tail gas purification system, a flue gas driving device 10 is provided before the leaching pretreatment device, and the flue gas driving device comprises at least two induced draft fans 11 arranged in parallel between the total flue gas input pipeline and the total flue gas output pipeline, and valves are provided at the inlet and outlet of each induced draft fan 11. Currently, the switching between the induced draft fans 11 is achieved by opening and closing control of these valves. The inventors found that: these valves are difficult to achieve complete sealing, and the yellow phosphorus tail gas is a flammable, explosive and highly toxic gas. When the switching between the induced draft fans is achieved by opening and closing control of these valves, backflow is likely to occur, which poses certain safety hazards.

[0095] In one embodiment of the present invention, the above-mentioned flue gas driving device is improved, and the flue gas driving device is adjusted between the leaching pretreatment device and the dephosphorization device 7. In addition, Figure 2As shown, the inlet of each induced draft fan in the two induced draft fans 11 is connected to the main flue gas input pipeline through an independently arranged first non-return liquid sealing device 12, and the outlet of each induced draft fan in the at least two induced draft fans 11 is connected to the main flue gas output pipeline through a uniformly arranged second non-return liquid sealing device 13.

[0096] Among them, the first anti-return liquid sealing device 12 includes a first closed liquid storage tank, a first vertical flow guide tube is provided on the upper part of the first closed liquid storage tank, the bottom of the first vertical flow guide tube is immersed below the liquid level of the first closed liquid storage tank, the upper part of the first vertical flow guide tube is connected to the main flue gas input pipeline, and a first exhaust port is provided on the shell of the first closed liquid storage tank above the liquid level of the first closed liquid storage tank, and the first exhaust port is connected to the air inlet of the corresponding induced draft fan.

[0097] The second anti-return liquid seal device 13 includes a second closed liquid storage tank, and the upper part of the second closed liquid storage tank is provided with a second vertical guide tube corresponding to the at least two induced draft fans one by one, the bottom of each second vertical guide tube is immersed below the liquid level of the second closed liquid storage tank, the upper part of each second vertical guide tube is connected to the exhaust port of the corresponding induced draft fan, and the shell of the second closed liquid storage tank is provided with a second exhaust port above the liquid level of the first closed liquid storage tank, and the second exhaust port is connected to the total flue gas output pipe.

[0098] The flue gas driving device 10 adopts an operation mode of two induced draft fans, one for standby and the other for use, and its flue gas conveying process is: the yellow phosphorus tail gas to be treated first passes through the first closed liquid storage tank of the first non-return liquid seal device 12, and the flue gas enters from the upper part of the first vertical guide tube, passes through the part of the bottom of the first vertical guide tube immersed below the liquid surface, and enters the air inlet of the running induced draft fan 11 from the first exhaust port after passing through the liquid seal; the flue gas pressurized by the induced draft fan 12 enters the second non-return liquid seal device 13 from the exhaust port, passes through the upper part of the second vertical guide tube corresponding to the induced draft fan 12, passes through the part of the bottom of the second vertical guide tube immersed below the liquid surface of the second closed liquid storage tank, and finally enters the total flue gas output pipeline from the second exhaust port. When the running induced draft fan 11 needs to be repaired or rotated, the standby induced draft fan 11 starts to take over the conveying task, and the safety and reliability of the switching process of the induced draft fan 11 can be ensured by the independent first non-return liquid seal 12.

[0099] The advantages of this design are as follows: by arranging an independent first non-return liquid seal 12 at the inlet of the induced draft fan 11, gas backflow when the induced draft fan is stopped can be completely prevented; by arranging a unified second non-return liquid seal 13 at the outlet of the induced draft fan 11, it can prevent the backflow of downstream gas and reduce equipment investment.

[0100] Figure 3 for Figure 1 A partial enlarged view of the dephosphorization device. Figure 3 As shown, the first catalytic flue gas treatment device includes a drying system, which includes a first blower 14 and a heater 15 (which are arranged in a one-to-one correspondence with the first reactor 71, and are specifically used Figure 1 The heater 6 in the figure, when each first reactor is working, the flue gas to be treated is first heated by the heater 71 corresponding to the first reactor and then enters the first reactor) and a drying gas distribution network, the first blower 14 and the heater 15 are connected to each first reactor 71 through the drying gas distribution network, so that the airflow generated by the first blower 14 is heated by the heater 15 to form a drying gas and enters the first reactor 71 after the first catalyst is washed and regenerated and passes through the first catalyst of the first reactor 71. When the drying gas passes through the first catalyst, the regeneration liquid attached to the first catalyst evaporates and is discharged from the first reactor 71 after the catalyst is washed and regenerated along with the flow of the drying gas.

[0101] In addition, the drying gas distribution network includes a drying gas delivery pipeline for mixing the drying gas discharged from the first reactor after the first catalyst is washed and regenerated with the flue gas to be treated from other first reactors.

[0102] The working principle of the above drying system is: the airflow is generated by the first blower, and the drying gas is formed after being heated by the heater, and enters the first reactor after the first catalyst is washed and regenerated through the drying gas distribution network, so that the regeneration liquid attached to the first catalyst evaporates and is discharged with the drying gas; at the same time, the discharged drying gas is mixed with the flue gas to be treated from other first reactors through the drying gas distribution network. This design can quickly dry the first catalyst after washing and regeneration, improve the working efficiency of the dephosphorization device, and the mixing process can make full use of the heat of the drying gas.

[0103] The heater 15 has a dual role: on the one hand (during the washing and regeneration cycle of the first catalyst), it is used to heat the airflow generated by the first blower to form a drying gas, so that it has enough heat to enter the first reactor 71 after washing and regeneration, thereby evaporating and taking away the regeneration liquid attached to the first catalyst; on the other hand (during the working cycle of the first reactor), it is used to heat the flue gas to be treated to ensure that the flue gas temperature entering each first reactor 71 meets the catalytic reaction requirements. This dual-role design ensures both the drying effect of the first catalyst and the normal progress of the catalytic reaction.

[0104] In addition, the first catalytic flue gas treatment device also includes an oxygen supply system, which includes a second blower 16, an airflow regulating device 17 and an oxygen supply gas distribution network. The second blower 16 and the airflow regulating device 17 are connected to each first reactor through the oxygen supply gas distribution network, so that the airflow generated by the second blower 16 is adjusted by the airflow regulating device 17 to form oxygen supply gas and enters the flue gas to be treated of the corresponding first reactor. The oxygen concentration in the oxygen supply gas is greater than the oxygen concentration in the flue gas to be treated before mixing with the oxygen supply gas.

[0105] The oxygen supplementing gas is air. The airflow regulating device 17 comprises a main pipeline and a bypass pipeline arranged in parallel, wherein a first stop valve, a flow regulating valve and a second stop valve are sequentially connected in series on the main pipeline, and a third stop valve is arranged on the bypass pipeline.

[0106] The airflow regulating device 17 adopts a dual-circuit design with a main line and a bypass line in parallel, wherein a first stop valve, a flow regulating valve, and a second stop valve are sequentially arranged on the main line, and a third stop valve is arranged on the bypass line. This structure can not only achieve precise flow control through the flow regulating valve of the main line, but also provide a fast channel through the bypass line. At the same time, the dual-circuit design provides an operation backup function, and each valve can be independently maintained and replaced, which improves the reliability and maintenance convenience of the system while ensuring the adjustment accuracy.

[0107] In addition, each first reactor is provided with at least two layers of first catalysts, and the oxygen-supplementing gas distribution pipeline network can introduce the oxygen-supplementing gas into the air inlet side spaces of the at least two layers of first catalysts respectively.

[0108] By arranging at least two layers of first catalyst in each first reactor and using an oxygen-supplementing gas distribution pipeline to introduce oxygen-supplementing gas into the air inlet side space of each layer of catalyst, a multi-level oxygen-supplementing and catalytic reaction process is achieved. This layered oxygen-supplementing design can not only ensure that each layer of catalyst obtains sufficient oxygen supply, thereby improving the uniformity and efficiency of the catalytic reaction, but also achieve more precise reaction control by adjusting the amount of oxygen-supplementing in each layer, thereby effectively improving the overall catalytic conversion effect.

[0109] In addition, the oxygen supplementation system further comprises an air bag 18 which is arranged in series between the second blower 16 and the air flow adjustment device.

[0110] By arranging the air bag 18 in series between the second blower 16 and the air flow regulating device, the air flow pulsation from the second blower can be effectively buffered and stabilized. At the same time, the air bag as an air storage device can balance the system pressure fluctuation and provide a stable air source for the air flow regulating device. This design not only improves the operating stability of the oxygen supplementation system, but also makes the air flow regulation more precise and controllable, thereby ensuring the safe and reliable operation of the entire system.

[0111] The working principle of the above-mentioned oxygen supply system is: the second blower 16 generates an air flow, the flow is adjusted by the main pipeline (including the first stop valve, the flow regulating valve and the second stop valve) arranged in parallel, and is introduced into the air inlet side space of at least two layers of the first catalyst of each first reactor through the oxygen supply gas distribution pipeline network, and an air bag 18 is arranged between the second blower 16 and the air flow regulating device 17; this design avoids the safety hazards that may be caused by mixed oxygen supply outside the first reactor 71 by directly supplying oxygen inside the first reactor 71 and accurately controlling the flow and distribution of the oxygen supply gas, and the setting of the air bag 18 can reduce air flow fluctuations and ensure the stability of oxygen supply.

[0112] The above is a description of the relevant contents of the present invention. A person skilled in the art will be able to implement the present invention based on these descriptions. Based on the above contents of this specification, all other embodiments obtained by a person skilled in the art without making creative work should fall within the scope of the present invention.

Claims

1. A flue gas purification system, comprising a flue gas purification device and a flue gas driving device for driving the flue gas to be treated to pass through the flue gas purification device, wherein the flue gas driving device comprises at least two induced draft fans arranged in parallel between a flue gas main input pipe and a flue gas main output pipe, characterized in that: The inlet of each of the at least two induced draft fans is connected to the main smoke input pipeline through an independently arranged first non-return liquid sealing device, and the outlet of each of the at least two induced draft fans is connected to the main smoke output pipeline through a uniformly arranged second non-return liquid sealing device.

2. The flue gas purification system according to claim 1, characterized in that: The first non-return liquid seal includes a first closed liquid storage tank, a first vertical flow guide tube is provided on the upper part of the first closed liquid storage tank, the bottom of the first vertical flow guide tube is immersed below the liquid level of the first closed liquid storage tank, the upper part of the first vertical flow guide tube is connected to the main flue gas input pipeline, and a first exhaust port is provided on the shell of the first closed liquid storage tank above the liquid level of the first closed liquid storage tank, and the first exhaust port is connected to the air inlet of the corresponding induced draft fan.

3. The flue gas purification system according to claim 1, characterized in that: The second non-return liquid seal includes a second closed liquid storage tank, and the upper part of the second closed liquid storage tank is provided with a second vertical guide tube corresponding to the at least two induced draft fans one by one, the bottom of each second vertical guide tube is immersed below the liquid level of the second closed liquid storage tank, the upper part of each second vertical guide tube is connected to the exhaust port of the corresponding induced draft fan, and the shell of the second closed liquid storage tank is provided with a second exhaust port above the liquid level of the first closed liquid storage tank, and the second exhaust port is connected to the total smoke output pipe.

4. The flue gas purification system according to any one of claims 1 to 3, characterized in that: The flue gas to be treated is yellow phosphorus tail gas.

5. The flue gas purification system according to claim 4, characterized in that: The flue gas purification device comprises: A dephosphorization device is used to receive yellow phosphorus tail gas and remove phosphorus-containing substances in the yellow phosphorus tail gas. The dephosphorization device adopts a first catalytic flue gas treatment device. The first catalytic flue gas treatment device includes a first reactor. When working, the yellow phosphorus tail gas enters the first reactor from the air inlet of the first reactor, passes through the first catalyst, and is then discharged from the exhaust port of the first reactor to become dephosphorized flue gas. PH3 and P4 in the yellow phosphorus tail gas react on the first catalyst to form phosphorus oxides and phosphoric acid when passing through the first catalyst. When the first catalyst is washed and regenerated, the phosphorus oxides and the phosphoric acid enter the regeneration liquid sprayed on the first catalyst and are discharged from the discharge port of the first reactor. An organic sulfur hydrolysis conversion device is used to receive the dephosphorized flue gas and convert the organic sulfur in the dephosphorized flue gas into H2S. The organic sulfur hydrolysis conversion device adopts a second catalytic flue gas treatment device. The second catalytic flue gas treatment device includes a second reactor. When working, the dephosphorized flue gas enters the second reactor from the air inlet of the second reactor, passes through the second catalyst, and is discharged from the exhaust port of the second reactor to become organic sulfur hydrolysis conversion flue gas. The organic sulfur in the dephosphorized flue gas is hydrolyzed and converted into H2S when passing through the second catalyst. A desulfurization device is used to receive the organic sulfur hydrolysis conversion flue gas and remove H2S in the organic sulfur hydrolysis conversion flue gas. The desulfurization device adopts a third catalytic flue gas treatment device, and the third catalytic flue gas treatment device includes a third reactor. When working, the organic sulfur hydrolysis conversion flue gas enters the third reactor from the air inlet of the third reactor, passes through the third catalyst, and is then discharged from the exhaust port of the third reactor to become desulfurized flue gas. When passing through the third catalyst, the H2S in the organic sulfur hydrolysis conversion flue gas reacts on the third catalyst to form elemental S and sulfuric acid. The sulfuric acid is generated by further catalytic oxidation of sulfur dioxide generated by the reaction of the elemental S with oxygen and reacting with water. When washing and regenerating the third catalyst, the elemental S and the sulfuric acid enter the regeneration liquid sprayed on the third catalyst and are discharged from the discharge port of the third reactor.

6. The flue gas purification system according to claim 5, characterized in that: The flue gas purification device includes a leaching pretreatment device, which is arranged before the dephosphorization device and is used to perform leaching pretreatment on the yellow phosphorus tail gas before sending it to the dephosphorization device; the leaching pretreatment includes a first leaching system and / or a second leaching system, the first leaching system is used to perform water leaching treatment on the yellow phosphorus tail gas, and the second leaching system is used to perform alkaline solution leaching treatment on the yellow phosphorus tail gas; The flue gas driving device is located before the elution pretreatment device or between the elution pretreatment device and the dephosphorization device.

7. The flue gas purification system according to claim 6, characterized in that: The first elution system comprises at least two first elution towers, and the second elution system comprises at least one second elution tower, wherein the second elution tower is arranged in series after the at least two first elution towers.

8. The flue gas purification system according to claim 6, characterized in that: A gas-liquid separation device and a gas heating device are sequentially arranged between the elution pretreatment device and the dephosphorization device.

9. The flue gas purification system according to claim 5, characterized in that:

1. The operating conditions of the first reactor are: 1) First catalyst formula: The first catalyst is mainly composed of the following components in parts by weight uniformly mixed: Nano PdO particles: 0.8-1.2 parts; Nano PtO2 particles: 0.4-0.6 parts; CeO2: 3.5-4.5 parts; V2O5: 2.5-3.5 parts; Activated carbon carrier: 90-93 parts; Wherein, the weight ratio of nano-PdO particles to nano-PtO2 particles is (1.8-2):1, and the weight ratio of CeO2 to V2O5 is (1.2-1.5):1; 2) Operation parameters of the first reactor: operate at 100-120℃, control the air velocity to 1000-2000h -1 , O2 concentration in the gas phase is 5-8% (v / v%), and the moisture content is less than 2% (v / v%); 2. The operating conditions of the second reactor are: 1) Second catalyst formula: The second catalyst is mainly composed of the following components in parts by weight uniformly mixed: CeO2: 5-7 parts; V2O5: 3-4 parts; MoO3: 2-3 parts; γ-Al2O3 carrier: 86-90 parts; Among them, the weight ratio of CeO2 to V2O5 is (1.6-1.8):1, and the weight ratio of V2O5 to MoO3 is (1.4-1.6):1; 2) Operation parameters of the second reactor: operate at 70-90°C and control the air velocity to 1000-2000h -1 , moisture content is 15-20% (v / v%); 3. The operating conditions of the third reactor are: 1) The third catalyst formula: The third catalyst is mainly composed of the following components in parts by weight uniformly mixed: Fe2O3: 3-5 parts; CuO: 2-3 parts; MnO2: 1-2 parts; Activated carbon carrier: 90-94 parts; Wherein, the weight ratio of Fe2O3 to CuO is (1.5-1.8):1, and the weight ratio of CuO to MnO2 is (1.8-2.0):1; 2) Operation parameters of the third reactor: Run at 65-85℃, control airspeed at 800-1500h -1 , the O2 concentration in the gas phase is 3-5% (v / v%), and the moisture content is 2-8% (v / v%).

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